Machine-switching telephone-exchange system



June 2, 1925.

L. POLINKOWSKY MACHINE SWITCHING TELEPHONE EXCHANGE SYSTEM Filed Oct. 18 1918 4 Sheets-Sheet 1 F410 5, mid

L. POLINKOWSKY MACHINE SWITCHING TELEPHONE EXCHANGE SYSTEM Filed Oct. 18. 1918 4 Sheets-Sheet 2 June 1925, 1,540,033

L. POLINKOWSKY MACHINE SWITCHING TELEPHONE EXCHANGE SYSTEM Filed Oct. 8. 1918 4 Sheets-Sheet a 22 7 2 o 4.7m, l'

,1 23/ g 208 291-7 14 f aes 305 Jun 2, 1925. 1,540,033

L. POLINKOWSKY MACHINE SWITCHING TELEPHONE EXCHANGE SYSTEM Fil ed Oct. 1918 4 heets-Sheet 4 I I p g 2352 Z Z a D D F a n :I a o Q: 1.7: l 1 2% I? 17 I 450! Fly. 4.

I m6 @122; 5/5 5/7 2 3 i m2 mm. m

y my

Patented June 2, 1925.

UNITED rares- PATE T ofrzFziqcs.

LIPAIIOIiINKOWSKY, OF"LO NDON, ENGLAND, .ASSIGNORTOWESTERN ELECTRIC ZOOM- PA'NY, INCORPORATED, '.OFNEW"YOBK, N. Y.,' A TGORPGRATIDN "0F 'N'EW YORK.

*M-AOHINE SWI'ECHENG TELEPHONE-EXCHANGE SYSTEM.

Applicationifile'diflctober 518, 19.18.. :Serial No. 258,682.

To all whom 25 may conccwt Be "it alznown that :I, LIPA Ponmnowsnu, a citizen of Russia, :residing :at 70 Westhourne Terrace, Hyde Park, London, iii V England, have invented certain new and useful Improvements in Machine-Switching il elephone-Exchange Systems, of which the following is :a ifull, clear, concise, lend :EZXElCt description.

This "invention relates .to machine switching itelephone exchange systems and more particularly to telephone exchange systems of the semi-automatic type in which connecti ons are extended over operators positions, at which cells receive full supervision, the releaseoi the cal]. remainsnnder:thecontrol ott the operatoig-and the-meter ofltheicalling line is operated during therelease of-a-successst'ully established connection. The :object of this iinvention is ithe improvement of systems of theaabove character in which service is given to an area .in whichzare also located satellites :associated with the :main exchange.

A featureloixthe invention is the provision at circuitszand .oppara tus :i'or extending calls over .a satellite ECO t-he switches of an op erators position :in an exchange, and for giving at the operutors :position, ithe same t'ull supervision, including" control lei" virelease. etc, :for the calls extended over the satellite, as for -calls originating :in ithe exchange.

In seniiaiutomutic changes of :theehove clnirscter means are provided for :holdingm train oil-switches, used 'in extending; a connectiou, in a predetermined condition, *hut freeing?theuterniinals (it hothithe calling and calledsubscrihec-s lines. 7

A "further feature 'ot the invention is the provision of means, associated with the switch in lilllE satellite and the trunk dine extending from the htellite to ztheiexchann'e, for freeing :the terminals I of the calling suhserihers line :and holding the switch, used in extending the call, in a predetermined condition, whenithe switches in? the exchange are'hrought into a holdover condition.

Another feature of thei'invention .is the provision of means associated with the switch ottlle satellite, for extendinga call, initiated in the satellite, to the switches in the exchainz e,independent of the-subsequent condition of the subscribers line initiating such call, andmeans, located in the satell-ite and operating in response to :a condition created over the switches of thezexchange to which such call has been extended, :removing in thesatell'ite the calling condition so -as to cause the transfer over the satellite (of ithe condition or" the calling line to the'supervisory means at the switches of the era change.

In the drawings:

Figure 1 shows asiihscrihers line and first/line 'finder ins-satellite.

igureB shows atrunk line for cellsout going from the satellite to the exchange. This figure also shows a local -suhscriher s line terminating in the 'finder at the .exchange.

Figure 3 ShOVVStElcord consisting ofasec- 0nd line finder, and=a tirstgroup selectorin the exchange. V

Figure A shows the searching sequence switch of ithe-cord and an 'operators, posi tion indicated as dares is essential for the understanding of the system The system disclosed asiembodied 1in I the present invention will he best understood fro1n=a descriptionaof-the operation thereof.

WVhen rthereceiver is removed onza subscriber station and 'line relay 1101 is energized rover :thesubscriber rline,-1a circuit is closed over -front contact of relay 10.1 for the en ergization of the ICOH'LIDOH starting :relays 10 i ot'the line fiu'cle11nroup including the individual :resistsnce 102 and 103, and both windings oi eachcommonastartiiigmelaw. A ipotentiel'is'therehy created on-terininal 110. The power magnet 1:11 oi'each free-first :line finder in the groupie energized in a circuit including contact 1 16 hottom of sequence switch 120 individual to the linei 'fin'der, hack :contact of-test relay 1'12, contact 117 top of sequence switch i120 and ifront-econtacts ofzreluyslO. 'When the line finder reaches l the terminals of the .calling "line the righthand winding 1 of 'test irelay ililf l is energized in .a circuit LOVQI :terminal illO, :relay 1L4 bring's LOVGT its front contact its le'ithantl low iresistance \winding in parallel to :its .righthand :high resistance winding and on terminal 1.10 is created .a busy potential. .V'henthe ibruslrcarriag e 1S centered and its coi'itact 119 is opens-i1. the

.252 to battery.

short-circuiting around winding of relay 112 is removed and this relay is energized, dis connecting on its back contact p'ower magnet 111 and connecting over its front contact a circuit for the energization of sequence switch 120 including its contact 122 top. In parallel to the sequence switch 120 is also connected over its contact 124, bottom, the holding magnet 115 of the line finder, the brush carriage is arrested, whereas sequence switch 120 starts from position 1 and under the control of its local contact 121 moves into position 5. In position 3 of sequence switch 120 a circuit is established for the energization of the cut-off relay 107 over terminal 118, letthand back contact of relay 113 and sequence switch contact 123, bottom. Relay 107 disconnects relay 101 and this in turn causes the de-energization of relays 104 and 114; also the power magnets of the remaining free first line finders are de-energized and these line finders are arrested. The magnet of the message register 108 is also included in parallel with cut-oll relay 107 but does not receive sufiicient current to operate at this time. As soon as relay 114 is de-energized, relay 127 is energized in a circuit over sequence switch contact 116, top, righthand back contact of relay 113, back contact of relay 114 and winding of relay 112. In position 4 of sequence switch 120 the lefthand windings of repeating coil 129 and the supervisory relay 131 are connected with the subscribers line over sequence switch contacts 125 and 126,

bottom, and both front contacts of relay 127. Relay 131 is thereby energized. In position 5 of sequence switch 120 the righthand winding of relay 137 is connected in bridge to the trunk line 140 over sequence switch contacts 128 bottom and 130 bottom. The winding 01' relay 151 in the exchange being of high resistance hinders the energization of relay 137. Relay 151 provides over its front contact a circuit for the energization of the common starting relays 154 including the individual resistance 152 and 153. Over resistance 155 and righthand back contact of cut-off relay 156 a potential is created on terminal 230. A second line finder in the exchange, as shown in Figure 2, then obtains a connection with the calling trunk line 140 which leads from the satellite shown in Fig. 1 to the terminal bank of the second line the call is extended to an operators position.

The start relays 154, on energizing, com

plete a circuit from ground over their armatures and contacts, conductor 105, contact 312, contact 211, bottom, winding of relay Relay 252 energizes and closes a circuit from ground through its armature and front contact, armature and back contact of relay 262, contact 212, top, winding of the power magnet 261 to battery.

Power magnet 261 causes the brush carriage of the line finder switch to rotate to search for the calling trunk line. Then the test brush 201 encounters the test terminal 230 of the calling trunk 140, a circuit is closed from battery through the inner windings oi relays 154, resistance 152, contact and armature or relay 151, resistance 155, back contact and right-hand armature of relay 156, terminal 230, brush 201, contact 215, bottom, right-hand high resistance winding of relay 264, contact 301, contact 202, bottom, to ground. Test relay 264 operates and completes a circuit through its left-hand low resistance winding and contact and armature and the winding of relay 262 to ground in shunt of the right-hand high resistance winding. When the brushes of the line finder are accurately centered, the contact 203 is opened and relay 262 operates to open the circuit of the power magnet 261, causing the line finder switch to come to rest in engagement with the terminals of the calling trunk line. The low resistance right-hand winding of relay 264 reduces the potential on terminal 230 and its multiples to render the trunk non-selectable to other switches. Relay 262 also closes a circuit from battery through the winding of sequence switch magnet 250, contact 204, bottom, front contact and armature of relay 262, front contact and armature of relay 252 to ground. Sequence switch 250 advances out of position 1.

On leaving position 1 sequence switch 250 opens the original energizing circuit of relay 252, but this relay is again energized in the following circuit as soon as the sequence switch reaches position 2; battery, through the winding of relay 252, contact 217, top, contact 205, bottom, of sequence switch 220, back contact and armature of relay 242 to ground. As sequence switch 250 passes through position 2 a circuit is completed from battery through the winding of sequence switch magnet 220, contact 206, bottom, contact 218, bottom, back contact and left-hand armature of relay 263, contact 210, top, to ground. Sequence switch 220 energizes in this circuit and moves out of position 1 and into position 4. Immediately that sequence switch 250 reaches position 2 a circuit is established from battery through the right-hand Winding of relay 157, terminal 207, brush 208, winding of relay 227, back contact and left-hand armature of relay 225, normal contact of relay 224, contact 216, top, to ground. It will be noted that relays 158 and 159 are included in parallel with this circuit, but the current flowing is insutficient to cause their operation. Relay 157, however, attracts its armature and closes a circuit for the cutoff relay 156, Relay 156 opens the circuit for relay 151 which removes battery potential from terminal 230 and also permits the deenergization of the start relays 154 to disconnect grou-nu'h-om the common start conductor 105,caus1-ng"al l other line tinder switches to cease hunting.

said sequence switch will stopin positioneu hit the time relay 157 0})t 3'1 at8Stl161'Glu-y 227 is energizedina circuit therewith and also attracts its armaturesr Relay 227 establishes circuit tronibattery through the lower left-hand winding of repeating coil 229, supervisory relay 231, contact 232, top, right -hand armature and trout contact of relay 227, thence over the lower side oi the trunk 1 10, contact 128,'bottoni,right-hand winding of relay 137, contactl30, bottom, over the upper side of the trunk .140, front contact and left-hand armature of relay 227,

contact 209, top, upper left-hand winding of repeating coil 229 to ground, M A flow of current in this circuit is suttici'ent' to operate giual relay 137 in the satellite otncethe mar Relay 17, on energizing, COIHPlGtGSfl, circuit troin battery through the winding-oi sequence switch magnet 120, contac 13",

bottom, front Contact and armature of relay 13'? to ground. Sequence switch 120 becomes energized in this circuit and moves out of position 5 and into position 0. The supen visory relay 231 is also energized in series with the relay 137 and remains energized in position 6 ct sequence switch 120 over a temporary circuit closed at the top of con= tact 133. Before this temporary circuit is opened to permit the deenergization of relay 281, contacts 130 and 128, top, are closedto extend the conductors. of the trunk 140 through the right-hand windings of repeat ing' coil 129 to the windings of relay 132. Since the calling suhs(:1-ibei"s receiver is off the switch hook at this tim-e,the supervisory relay 131 is energized and at its armature and contact shunts out the left-hand high 7 resistance winding of relay 122 so that only of the supervisory lamp 245. At the instant the sequence switch 120 passes into position 6, relay 132 operates, as explained, and at its armature and contact closes a shuntaround the winding of relay 112. Relay 112 there? upon deenergizes prior to the arrivalot sequence switch 120 in position 9.

In position 4: of sequence switch 220 a circuit is closed frombattery through the winding of relay 308, lamp 270, contact 218, top, back co 7' and left-hand armature 0t rt.- lay 263, contact 210, topto ground. Lamp 2?0 is illuminated and relay 3-08 is energized other searching sequence switches.

to close alightin g circuit for lamp- 87 2. The illumination of these lampsapprises the operator tl'rat call is In position at of sequence swit-h 250 the sender searching sequence switcn 336 is operatcdto associate the cord circuit, illustratai'vaitin-g' her attention, I

ed in Fig. 3, with an idle register sender.

mechanism, The circuit for sequence switch 3-80 may be traced from battery through the windings of relay 813, u' i nd-ing of sequence switch magnet 330,contact 2'19, bottom, bar-h contact and armature of relay 262, front contact and armature of relay 252 to griiund. The sequence switch 330 commences to rotate and as soon as an idle register sender is tound a testcircuit is completed from battery' through the contact and lett hand arm of relay 31er'contact 8-15, contact 316, hand winding of relay 805, contact 306, contact 222, bottom,right-hand winding of relay 2641', contact 302, bottom, of sequence switch 330to ground, Due tothe presence of se lectable potentialat the contact 306 corresponding to the idle register sender, illus trated at the lower right-hand part of 1, the relay 264 receives sutlicient; current throughits high resistance winding; to oper-v atc.- Relay immediately completes acircuit through its left-hand low resistancewinding and the winding of relay 262 in shunt of its high resistancewinding, thereby reducing the potentialon terminal 306 torender the selected register sender lousy to Relay 262 operates and opens the circuit of sequence switch 330 causing the same to stop and also: completes a circuit fronrhatt'ery through the winding of sequence switch magnet 250-, contact 20 1, bottom, front contact and armature, of relay 262, front coir tact and armature of relay 252 to ground.

Sequence switch 250 leaves position t, moves over position 5 and into position 8. In leaving position 5 the circuit of relay is opened. and this relay becomes deener ed, Also as sequence switch 250 leaves po 5 it opens contact 222, bottom, and permits the deencrgization oil" relays 264 and 262. Sequence switch 250, upon passing position 6, closes a circuit from battery through the winding of sequence switch 220, contact 223, bottom, contact 226, top, back con-tact and rigl1t-hand armature of relay 225 to ground. The momentary closure of this circuit causes the energization of sequence switch 220 which advances out of position i and into position 5. The lamps 270 and 372 are now caused to flash by the interrupter 236 which is included in a circuit traceable over C0111 tact- 228, bottom, lamp 270, relay 308 to ground. It will benoted that the original circuit for the steady illumination of these lamps is opened at contact 218,- top, when sequence switch leaves position 6. The flashing of the lamps 2T0 and indicates I to the operator that an idleregister conserves to position registers, which, in turn,

operate to control the selective movement of group selector switches to'extend the incoming trunk 1.40 through to the called subscribers line. The operators keyboard, the registersand the various other elements of the register controlling mechanism have been omitted from the disclosure for the sake of simplicity. Controlling mechanisms of this general character are, however, nu-

merous and well-known in the art, and since,

the register sender plays no important part in the subject matter of the present invention, it has not been shown in full. The register sender mechanism, among other elements, is provided with a sequence switch 310, which, in the usual manner, advances from position to position .during the progress of setting up the connection on the registers and during the progress'of controlling the several selective switches tobring about the necessary circuit changes, for this purpose. I a

Referring to the elements of the sender which-have been shown in the drawing, it

will be recalled that the relay 305 was included in the test circuit with relay 264 and relay 262 at the time the register sender was selected by the searching sequence switch 330. Relay 305 operates and closes a circuit from battery through its lefthand winding and contact and left-hand armature, contact 317, right-hand winding of relay 305, and thence over the conductor 318 to ground. Relay 305,0n operating, closes a circuit from battery through the winding of sequence switch magnet 310, contact 319, lower, front contact and righthand armature of relay 305 to ground driving said sequence switch out of position 1 and into position 5. After the'number has been set up on the operators keyboard a circuit is closed in any well-known manner for, advancing the sequence switch 310 into position 7. In this position of sequence switch 310 a circuit is completed from battery through the winding of sequence switch 220, contact 214, bottom, contact 303, contact 304, front contact and right-hand armature of relay 305 to ground. Sequence switch 220 moves out of position 5 andinto position 8 and in so doing disconnects the operators telephone set from talking relation with the subscribers line. 8 of sequence switch 220 a circuit is closed from battery through lamp 340, contact 238,

interrupter 236 to ground, whereby the lamp- 340 is intermittently illuminated.

When the register sender is completely prepared to control selection its sequence switch 310 will have advanced into some,

.to ground. Relay 252 operates and closes a circuit from battery through the winding of sequence switch magnet 250, contact 233, bottom, the back contact and armature of relay 262, front contact and armature of relay 252 to ground, driving sequence switch 250 into position 9. Brush selection now takes place at the first group selector switch and for this purpose a circuit is closed from battery through the magnet of the trip. spindle 273, contact 221, bottom, front contact and armature of relay 252 to ground. The trip spindle isrotated and foreach brush tripping position a circuit is closed from battery through the winding of relay 252, contact 211, top, to ground at the interrupter contacts 2751 This circuit causes the shunt of the stepping relay 324 in the well-known manner, which, in

turn, causes the advance of the register, not

shown. When the proper set of brushes has been reached the fundamental circuit is opened at the sender and relay 252 becomes deenergized as soon as theinterrupter contacts 275 are opened thereafter. Relay 252 severs the circuit of the trip spindle magnet and completes a circuit from ground through its armature and back contact, con tact 204, top, winding of sequence switch magnet 250 tobattery. Sequence switch 250 leaves position 9 and as soon as it reaches position 10 relay 252 is again energized over a circuit including contact 217, top, contact 214, top, of sequence switch 220, contact 303, contact 304, front contact and right-hand armature of relay 305 to ground. Relay 252 attracts its armature and opens the circuit of sequence switch magnet 250, whereby said sequence switch comes to rest in position 10. I

The brush carriage of the group selector is rotated to advance the tripped set ofv brushes over the terminals of the bank to search for an idle trunk. For this purpose a circuit is closed from battery through the winding ofthe brush carriage power magnet 28l,'contact 212, bottom, back contact and armature of relay'262, front Contact and armature of relay 252 to ground. WVhen the brush 270 encounters the test terminal of In position lli lilil d ii iii? tact of said rel.

the first idle trunk, a selectable potential GXlStlllg thereon, a circuit 153 closed over said brush, contact. 215,, top, right-hand highrewinding of sequence switch magnet 250 ,0011- tact 20%, bottom, front contact and armature of relay 20-2, front contact and armature of relay 2-52 to ground, driving sequence switch 250 over position 11 and into position 12.

The fundamental circuit is now extended over contacts 309 and 311 and contacts 231'? and 238 to the next succeeding selector. switch in the train. In the ivc-lldrnown manner the register controlling mechanism causes the selective movement. 01: the succecding switches and-the connectionis extended through to the called subscribers line. i

Following the last selective movement of the final switch, the controlling switch. 310 of the register mechanism, having advanced to a position where the circuit of relays 3105 is vopened, this relay becomes deenergized and opens the circuit of relay 252. Relay 252 releases its armature and closes a circuit from battery through the winding of sequence switch 250, contact 204;, top, hack contact and armature of relay 252 to ground. Sequence switch 250 1noves out of position 1 and into position 14%. During the operation of the final switch, not shown in this disclosure, the controlling sequence switch thereof. in passing from one position to an other following the completion of selection, closes a temporary short-circuit across the line conductors, which completes a circuit for supervisory relay 242 including the rig it-hand windings of repeating coil. 229. Re I 2 12 attracts its armature and closes a uit including the contact 200, top, :Eor ,3 sequence switch 220 out oi: position 8 and into position 9. later, the short-circuit across opened at the final. switch relay 2 12 becomes deenergir-ied and circuit is closed. from ground through the armature-mid hack cony, contact 223, top, winding of sequence switchinagnet Sequence ch 220 leaves position 9 and noves into position 11. The manner in which the shortcircuit is temporarily line conductor-s at, the final selector switch circ is illustrated and described in applicants hen, an instant the line 1s established across the 240, contact 205, top, llliiillirflOllili'iCt and 211 11111 ture ot-jrelay 2412to ground. 'lfhe'illuininm' tionroi-lainp 2 10 notifies the operator of the. fact tllfii] the .calledline has heen selected and ringing current is being applied thereto.

The response of the called subscriber -rc-. sults in the closure ofthe linecircuit' in so rice with the right-hand windings of repeating coil 2,29 and the consequent encrgization of relay 2 12. The circuiti's thenclosedineluding contact 206, top, for advancing sequence switch 220 into position 14;. The lamp 2&0 is extinguished,notifying the operator that the called subscribed has an swercd, 1 7 7 .At the completion of conversation both the calling and called subscribers.replace their receivers on the switch hooks. The opening of thecalling line causes the deenergication of relay 132. The high resistance of relay 132 being included iii-series with relay 231, the flow of current is so diininishedthat relay 231 releases its armature. A circuit is, therefore, established frombattery through thelamp 24:5, contact 213 to ground atthe armature and contact of relay 213. The

opening of the called subscribers line perunits the deenergizationgof relay 21:42 which completes a circuit from. battery through lamp 2355, contact 23 1, top, back contactv and arina-ture of relay 242 to ground, The operator, observing the illumination of both -v lamps 245 and 235, is aware that t-he'sulr scribers have replacedtherr receivers on the switch hooks and that the connection isno longer required. 1 She. then proceeds to release by actuating the key280.

Upon the actuation of key 280 a circuit is closed from battery through the left-hand winding of release relay 263, contact ofkey 280, "contact 213, cont-act and armature of I relay'2'31 to ground. Relay: 263 operates and locks in a circuit from battery through its right-hand]winding, .f-ront contact. and right-hand armaturc, con;taot 202,,top, to ground. Relay 263 closes :a circuitiTom battery thrcugh the winding oiscquence switch nagnet250, front contact and left hand armature of relay 2.63, contact 210, top, to ground. Sequence switch 250 lea-Yes posi-- tion 14-. hen sequenceswitch 250 reaches position 15a circuit is closed frorubattery through the winding of sequence] switch magnet 220, contact 223, bottom, contact 226., top, back contact and right-hand armature of relay to ground, Sequence switch 220 leaves position 14: and colninences'to rotate into its normal position 1. While sequence switch 220' islpassing from position 16 to position 18;; circuit is closed from. the source of metering current 359, key 3641,, contact 3116. bottom, normal contacts of 22:4... 1e

hand armature and back contact of relay 225, winding of relay 227, and thence in parallel to the right-hand windingvof relay 157 and the windings of relays 158 and 159. The source 359 increases thefiow of current in the circuit traced to an extent sufficient to cause the operationof relays 158 and 159. Relays 158 and 159 connect the opposite poles of batteries 161- and 162 to the two sides of the trunk 140 leading back to the satellite ofi ice.

At the time sequence switch 220 leaves position'14on its way to normal, contact 232 is opened and consequently the relay 132 becomes deenergized. Relay 132 removes the shunt from around the winding of relay 112 and this relay again operates in series with relay 127. Relay 112 completes a circuit from ground through the contact 117, bottom, armature and front contact of relay 112, contact 122, top, winding of sequence switch'magnet 120 to battery, driving said sequence switch out of position 9 into position 17. As sequence switch 120 reaches position 10, the trunk conductors 140 are connected by way of contacts 130 and 133 to the right-hand winding of marginal relay 137. The current flowing from the source 161, 162 is sufficient to' cause the operation of the marginal relay 137 which attracts its armature and locks in a circuit through its left-hand winding and contact 131, top. The function of this relay is,'as will be later explained, to permit or to hinder, as the case may be, the application of metering current to the calling subscribers line at the time of disconnection. In the present instance, since the call was successful, the calling subscribers meter 108 will be operated in the'manner about to be ex- 1.13, contact 118, winding ofmagnet of meter 108 to battery. Current-flowing in this circuit is suflicient to cause the operation of the meter magnet and the call is recorded against the subscribers line. In position 17 of sequence switch 120 a circuit is established from battery through the winding of the holding magnet 115, contact 124, top, lower right-hand winding of repeating coil 129, the windings of relay 132, upper right-hand winding ofsaid repeating coil contact 130, top, over the upper side of the trunk 140,

I back contact and "left-hand armature of relay157 to ground. It will benoted that relay 157 has, in the meantime, become deenergized following the opening of the contact 116, bottom, as sequence switch 220 leaves position 18. Relay 132, therefore,"becomes energized and reestablishes the shunt around the winding of relay 112. Relay 112 becomes deenergized and a circuit is closed from ground through the contact of relay 117, bottom, armature and back contact of relay 112, contact 122, bottom, winding of sequence switch magnet 120 to battery.

Sequence switch 120 moves out of position of relay 162, front contact and armature of relay 252 to ground, driving sequence switch 250 into-position 18. 011

leaving position 16 the circuit of test relays 264 and 262 is opened which may serve in any well-known manner to cause the release of the succeeding switches; In position 18 of sequence switch 250 a circuit is closed I from battery through the winding of the brush carriage power magnet 281, contact 212, bottom, and thence to ground at the Contact and armature of relay 252. The brush carriage rotates and upon reaching its normal position a circuit is'closed from battery through the winding of holding magnet 285, contact 241, top, brush 289 and its home contact, winding of relay 262 to ground. Relay 262 opens the circuit'of the power magnet 281 and closes a circuit from battery through the winding of sequence switch magnet 250,. contact 204, bottom, front contact and armature of relay 262,

front contact and armature of relay 252 to ground. The sequence switch thereupon moves into its normal position and relays 252, 262 and 263 become released.

Should the called subscribers line be busy at the time connection is extended thereto, the relay 242 is held permanently energized by means of the shortcircuit above referred to across the talking conductors at the final switch. Consequently, the sequence switch 220 advances out of position 8 upon the energization of relay 242, and remains in position 9 instead of moving immediately therefrom, as in the case of the line being idle. ith sequence switch 220 in position 9 the busy tone (1011 247 15 connected to the talking conductors and transmits a tone over notbe obtained, replace his receiver on the ill) switch hook, which opens the circuit otrelay 131: and permits-the" inclusion of the high resistance Winding of relay 1 82 in series With the relay 2351. Relay 231: energizes and causes the illumination of the supervisory lanip 235 The operator then initiates releaseloy dc-- pressing disconnect key 2803 It is to: beehserved that the distinction between: release after a successtu-lconnection and: releasefollowing the attempt of a connection to a busy line is that in: the latter case the so quencc switch 220 is only adyanced as far as pesition 9. heir, therefore, sequence switch 250 leaves position and movesthrongh position it does-'not; close-a cir cu-it for sequence switch 220, ashel'ore, at the contact 226, top, inasmuch as this cincuit is now held openedat contact 223, bottom. Consequently, sequence switch 220 remains in position 9 While sequence switch continues toadvance on into position 17.

Immediately that sequence switch 250 l'ea ves' position 16, contact 210, top; is openedand relays 227and= 157 become deenergizedi Relay- 227 closes acircuitfronrbattery througlr the right-hand winding 0 relay" 224 back contact andlett-hand arms (1 #:I'GOFlGltIY 227;

contactQOE), top, upper left-hand Windingot' Relay 22 1 operates-and locks in a circuit from battery thronglr it-s lett-han=d armature and front" repeatin'g coil 229* to ground.

contact and left-hand Winding to ground. heir sequcnceswitch 250leaves position 1 6,-

the test circuit leading:'orerhrush 2.76%0 the tein, contact 226, top, bacle contact and.

rightdiand armature of relay 225to=ground1 S silence switch 226) leaves position 11 and moves through position 1 1+ and i nto position 1. This time; howevenzthe normallcentacts at the right-hand armature of relay 224:, are

opened as sequence switch 220 passes through position 16 to 1)0S1ii1011-lf81, and consequently, the-metering battery is not? connected to the Windiicrs of relays 158 and 159;

Hence, the re 137' llli the satellite! ofii'c'e: remain inert during" the time that sequence.

switch 12 1 isadyancing: through positions As. a result a circuit" is closed? from battery through the left-h and awndmg;

otrelay 113,v centact 135, b(. ttom,. hackconact and armature of? relay 187 to ground. Relay 118 operates,opens-the circuit of relap- 127 and closes a circuit from: battery through contact 116;. top..ri ght-hand vWindofii'ce, is shown.

ing and front contact and right-hand 'armature'of relay 113, back contact and armature of relay 114, the Winding ot' 'relay: 1121 to: ground. Relay ll be-ing" energized at the time-sequence switch 120 moves to positions 14%and'16 the circuit'for the-application" 0t the metering source 123 is opened, and; consequently, the meter 108* is not operated? to charge the call against the suhscrihers line; Imposition 1-7 01 sequence switch 120,'relay 132-isoperatedgas above explainechand the sequence switch 120" is advanced into its normalposition, position 1. Furthermore, release. the switch at the exchange takes place in the manner already explained.

Intlie lower part of Fig. 2 a local suln 30 scribers line, terminating in the central As illustrated, this line terminates directly in: the multiples of the line finder switch shown in- Fig; 3; It Will be understood, of course, that a primary line finder, similar to'the one shown in Fig; i 1* of the satellite, may he installed whereby the localsuhscriher s line is-first extended over the primary switch and thenceto the terminal'bank of" the secondary line findershown'in 8. In eithercase, the ond' line finderhas access both tos-uhscril ers lines terminating locally inthe ore-- change and also incoming; trunk lines from distant satellite oiii'cesi When a local suhscriber, such, for example, as-thesubscriber: of line 1 11, initiates a call, the line relay 1'42 is--- operated and start relays, Sl-lnllilfil to" relay 154, are energized to initiate the movement ofthe second line; finder switches having access to said line: When the brushes 201, 208,"etc. o'f the line finder have seized the terminals of the local suhscrib'-- ers line, cut-off relay- 143- isoperated in the manner explained, and when atthe end of a successfully established connection re-- lease occurs, the source otn'ietering" current- 359- isconnected over thehrnsh 20S, precise-ly in the manner enpla inml above in dctail, to the Windingso'i the-cut-oil relay 14:3- and the message register magnet 1 1-4; Thus, the call is charged against'thc calling; snh scriher.

By such an arrangement the function of" thecord circuit and the apparatus at the operators-position is always the same regardless of 'the' nature of the incoming line, that Whether the calling lineis one ten niinatiiug locally in the cei'itral oiiiceor one which l. as been extended thereto over a, twoovireinteroilice trunk line. Inthe case oil: a local line,n1etei1'in'9 current is applied directly to the suhscri'h'ei"smeter individual to the line, Whereasiir the case: of a call from a distant satellite office, metering current is connected to the two-Wire trunk and in than causes the application of current s over the condiictors of said trunk leading back to the satellite otlice and there controls apparatus to cause the operation of the register individual to the calling line.

Should the operator in the central office desire for any reason to hold the switches of an established connection in their operated condition and at the same time to free the calling subscribers line in the satellite oflice, she may do so by depressing the key 239 in conjunction with the key 365. The actuation of these keys completes a circuit from battery traceable through the right-hand winding of relay 225 to ground. Relay 225 operates and opens the circuit of relay 227. Relay 227 releases and opens the circuit of relay 132 which becomes deenergized and removes the shunt from around the winding of relay 112. Relay 112 becomes energized and closes the above traced circuit for driving sequence switch 120 out of position 9 and into position 17. Since sequence switch 220 remain in position 14 the meter battery 359 is not connected to the relays 158 and 159 and hence relay 137 in the satellite remains deenergized. Consequently, relay 113 operates as sequence switch 120 passes position 13 and locks to prevent the application of metering battery 123 to the calling subscribers message register.

At the time relay 227 deenergizes the cincuit of relay 157 is also opened but relay 157, being slow to release in character, maintains its armature attracted until relay 227 has had time to completely retract its armature. A new circuit for relay 157 is then established from ground through the left-hand winding of said relay, front contact and right-hand armature of relay 156, terminal 230, brush 201, back contact and right-hand armature of relay 227, contact 232, top, winding of relay 231, the lower left-hand winding of repeating coil 229 to battery. Relay 157 remains energized and holds the circuit previously traced through the holding magnet 115 and the windings of relay 132 open at the time sequence switch 120 moves in position 17. Therefore, the sequence switch 120 is held in position 17 and the first line finder switch is maintained in its partially released condition so long as the connection is held at the central ollicc. The calling subscribefls line, however, is rendered free. The cut oil' relay 107 is deenergized after sequence switch 120 leaves position 13 and the calls ing subscribeus line is rendered free to ini tiate other calls. lVhen the operator decides to release the connection she may do so by depressing the release key 280 and release follows in the manner previously Clescribed Another feature of the system herein disclosed is the arrangement wherein a call,

once initiated in a satellite oflice, is extended through to the operators position, unmterrupted, notwithstanding the fact that the calling subscriber may abandon the call after having initiated the-movement of the first line finder switch. Once the line finder has found the calling subscribers line sequence switch 120 moves into position 5, as above described. Shortly thereafter the relay 132 is operated to shunt the relay 112 which completes a circuit for advancing the sequence switch 110 out of position 5 and into position 9. If the calling subscriber has abandoned the call, relay 131 becomes deenergized and removes the shunt around the high resistance winding 132. Consequently, relay 231 at the distant otfice becomes deenergized. The second line finder in the central otfice having operated in response to the actuation of relay 151 to find the trunk 140, sequence switch 250 is moved out of position 1 and into position 4-. Consequently, with the sequence switch 220 in position at and relay 131 deenergized, relay 231, as explained, is unable to maintain its armature attracted due to the high resistance of the left-hand winding of relay 132. A circuit is, therefore, closed from battery through the lamp 245, contact 213, armature and contact of relay 231 to ground. The operator seeing the lamp 245 illuminated knows the calling subscriber has prematurely abandoned the call and she proceeds to bring about the release of the connection by depressing the key 280.

What is claimed is l. A telephone exchange system comprising a main exchange and satellite exchanges, calling lines terminating at said exchanges, an operators position in said main exchange, trunk lines between said main exchange and said satellite exchanges, automatic means at said satellite exchanges for extending a calling line over one of said trunk lines from one of said satellite exchanges to said operators position in said main exchange, controlling means at said operators position, and means responsive to the operation of said controlling means for holding an automatic switch in a satellite exchange in the connection as established while the calling line is rendered free to call and to be called.

2. A telephone exchange system compris ing a line, an automatic switch, means for operating the automatic switch to extend said line, means controlled by said switch in its operated condition for rendering the line busy, means for rendering the line continually idle during the rest of the period said switch remains in its operated condition, and means for releasing said switch.

3. A telephone exchange system comprising a line, an automatic switch, terminals for the line in said switch. means for operating said switch into engagement with said terminals to extend said line, means controlled by said switch in its operated condition for rendering the line busy, means for rendering the line continually idle during the rest of the period said switch remains in engagement with the terminals thereof, and means for releasing said switch.

4. A telephone exchange system comprising a line, an automatic switch, a trunk, means for operating the automatic switch to extend said line over said trunk, means controlled by said switch in its operated position for rendering the line busy, means controlled over said trunk for rendering the line continually idle during the rest of the period said switch remains in its operated condition, and means for releasing said switch.

5. A telephone exchange system comprising a line, an operators position, an autoinatic switch, means for operating said switch to extend said line to the operators position, selective switches for further extending said line, means controlled by said automatic switch in its operated condition for rendering said line busy, means controlled by the operator for rendering the line idle while said switches are held in their operated condition, and means controlled by the operator for releasing said switches.

6. A telephone exchange system compris ing a line, a plurality of automatic switches, means responsive to a certain condition on said line for operating said switches in succession to extend said line, and means for releasing said switches, said switches ar ranged to continue in operation once their operation is initiated to extend said line regardless of the'suhsequent condition that may exist on said line.

7. A telephone exchange system comprising a line, an operators position, a plurality of automatic switches, means responsive to a calling condition on said line for operating said switches in succession to extend such line to the operators position, a signal at said position, means -for operating said signal when the calling condition is removed from said line, and means controlled by the operator for releasing the switches, said switches being arranged to continue in operation once their operation is intiated to extend the line to the operators position regardless of whether the calling condition on said line is maintained or is immediately removed.

In witness whereof, I hereunto subscribe my name this 16th day of August, A. D., 1918.

LIPA POLINKOWSKY. 

